1. Field of the Invention
The present invention relates to a hydraulically controlled engine mounting device for an automotive vehicle and more particularly, to a hydraulically controlled engine mounting device interposed between an engine and a body of an automotive vehicle, the device having plural hydraulic pressure chambers controlled by a single solenoid valve.
2. Description of the Prior Art
A hydraulically controlled engine mounting device of an automotive vehicle not only fixes and supports the engine but also prevents the vibration of the engine from being transmitted to the vehicle body.
The hydraulically controlled engine mounting device comprises an orifice between two hydraulic pressure rooms, and a fluid filled in the above hydraulic pressure rooms generates a fluid friction when passing through the above orifice by the vibration transmitted from the engine, whereby the vibration of the engine is damped.
At this time, the damping effect of the vibration depends on the length and the sectional area of the orifice interposed between two hydraulic pressure rooms.
However, since a lower frequency and a higher frequency of a vibration damp each other, the hydraulically controlled engine mounting device is generally designed so as to preponderantly damp the vibration of the lower frequency on the planning phase.
In such a case, the slight-vibration of the higher frequency not damped increases a dynamic spring constant of the engine mounting device, whereby the restraining effect of the transmission of the vibration is deteriorated.
To solve the above problem, there are some methods in which two groups respectively having a pair of the hydraulic pressure rooms are made, the first group being designed for the lower frequency and the second group being for the higher frequency, and then two groups of the hydraulic pressure rooms are selectively operated according to discrimination of the frequency of the vibration transmitted to the body, whereby the vibration is damped in all areas of the frequency of the vibration, and that a diaphragm is mounted inside the hydraulic pressure room and the vibration transmitted from the engine by the vibration of the diaphragm is offset.
However, the former has a problem that a structure of the engine equipping device is complex, and at the same time, a volume is enlarged, and in case of the latter, the damping effect of the vibration is not good.